Embodiments of the present disclosure relate to range extenders and circuit protection methods.
A range extender is an additional energy storage component mounted on an electric vehicle and configured to increase a mileage of the electric vehicle. In a normal operation mode of a range extender comprising a boost direct current converter, an output voltage of the range extender is higher than an input voltage, and closed-loop control is performed by a proportional-integral controller to stabilize the output voltage of the range extender. However, in case of a sudden increase in the electrical load, for example, an acceleration process of the electric vehicle, the output voltage will decrease suddenly, and then the proportional-integral controller will turn on switch device(s) located in a power transmission path of the range extender to pull up the output voltage. As a result, there is a positive voltage across an inductor in the power transmission path, which makes a current flowing through the inductor and the switch device increase rapidly. The switch device will be broken when the current increases to a value higher than a maximum current of the switch device. In some conventional methods, this problem is avoided by providing an over-current protection device. When the current increases to a value higher than a preset value, the over-current protection device will be triggered to turn off a main switch of the range extender to make the electrical load stop working, which will affect the normal operation of the electrical load. Especially for the electric vehicle, this will be very detrimental to users' driving safety.
Therefore, it is necessary to provide new range extenders and circuit protection methods to solve at least one of the above-mentioned problems.